Self-winding, manually operated, internal combustion engine starting units are widely used for power mowers, chain saws, and other devices which are powered by small internal combustion engines. Such devices employ pull starters for rotating the crank shaft of an internal combustion engine by means of self-rewinding, wrapped cord means which includes ing.
In the past, engine rewind pull starters have been developed wherein engagement for cranking of the engine occurs in the first very small travel of the starter rope. This is accomplished by attaching a hollow, circular shell to the crank shaft of the engine to be started. A starting pulley is then rotatably mounted upon a stationary pivot with a starting cord in wrapped engagement with the pulley. A retrieving spring resiliently engages the pulley so as to urge the pulley in a direction that will restore the wrap of the starting cord when displaced. The pulley carries outwardly movable clutch members which are positioned within the shell and are normally maintained out of contact with the shell. However, upon rotation of the pulley in the cranking direction of the engine, the clutch members are forced outwardly into contact with the shell to turn the engine crank shaft. An engine pull starter of this type is disclosed in U.S. Pat. No. 2,772,669 to W. E. Armstrong issued on Dec. 4, 1956, hereinafter referred to as the Armstrong patent.
Rewind starting devices of the type disclosed by the Armstrong patent are intended to provide rapid disengagement of the outwardly movable clutch members from the circular shell when the engine starts. However, it has been found that under certain severe starting conditions; for instance, when extremely high, rapid starting forces are applied, that the trailing edges of the clutch members or shoes fail to disengage from the shell when the starter cord is released or the engine starts. This failure to disengage immediately may result in severe damage to starter parts.
Also, failure of such rewind starting devices due to improper connection of the pulley rewind springs is prevalent. Since the rewind spring is behind the pulley, attachment of the spring during assembly of the starter must be done strictly by feel. This causes a certain percentage of production rewind springs to be improperly attached, and consequently the rewind mechanism for the pulley fails shortly after use.
It is a primary object of the present invention to provide a novel and improved rewind pull starter for an internal combustion engine which provides engagement for cranking in the first very small travel of a starter rope to preclude impact damage to the starter parts if the starter rope is jerked and which will disengage immediately upon starting of the engine.
Another object of the present invention is to provide a novel and improved rewind pull starter for an internal combustion engine which includes an improved starter pulley design to forceably disengage the starter clutch members when the engine starts.
A still further object of the present invention is to provide a novel and improved rewind pull starter for an internal combustion engine which includes an improved pulley design adapted to facilitate engagement of a rewind spring during starter assembly.